1. Technical Field
The present invention relates to a method and apparatus for compacting a slug of product.
2. Description of Related Art
Product often settles after it has been packaged making the package appear less than full. Thus, often a package appears full once it is manufactured, but after further settling appears less full. One example is that of a traditional flex bag containing snacks such as potato chips. Such flex bags are traditionally made and filled in a vertical form, fill, and seal machine. FIG. 1 depicts a portion of a traditional vertical form, fill, and seal machine. First, product is weighed and measured in a weigher 101. The weighers 101 collect and discharge a specified charge of product. Each charge represents the amount of product which will occupy a single bag. Downstream from the weigher 101 is typically a funnel 102 or a series of funnels which directs the product. As used herein, “downstream” and “upstream” refer to relative points or locations in the process or apparatus. Thus, an event taking place downstream occurs later in the process and follows events which took place upstream. Downstream from the funnel 102 is a product delivery cylinder 103. As used in a vertical form, fill, and seal machine, the product delivery cylinder 103 is often referred to as a former. The packaging film for the final package is wrapped around the product delivery cylinder 103 to form a tube. Once the lower portion of the tube is sealed, product is delivered through the product delivery cylinder 103 and into the sealed tube. Thereafter, the top portion of the tube is sealed, cut and separated from the upstream film, and a package is formed. The apparatus is a very effective bagmaker and can produce bag rates as high as 100 bags per minute.
During shipping and handling the product within the package begins to settle, increasing the void space at the top of the package. A package which has sat on a retail shelf, after transportation and handling, will often look less full than a package taken directly from the bagmaker. This results in a variety of problems. First, a package appearing and feeling less full is less appealing to a customer compared to a fuller package. Second, many consumers are unpleased to open a package to realize the package is about half full. Third, due to the increased void space after the product settles, the prior art package is larger than needed at this point relative to its contents. Such a package unnecessarily takes up valuable space on a retail shelf space, in shipping trucks, in warehouses, and in consumers' pantries. Further, manufacturing materials such as plastic films are wasted in forming such a package.
For the above reasons, attempts have been made to decrease the void space in a package. One attempt disclosed in commonly owned U.S. Publication No. 2006/0165859 which teaches that randomly shaped product tends to settle less over time than uniformly shaped product and thus discloses producing randomly shaped product. One drawback of this method, however, is that is it not always desirable to produce randomly shaped products.
Another known method is partially filling the package with product, vibrating the package to settle the product within the package. Thereafter additional product is added to the package and the process repeated. Unfortunately, this process is very slow and cannot be conducted at high rates on a traditional vertical form, fill, and seal machine.
Accordingly, one object of the instant invention is to provide an apparatus and method which results in increased compaction of product within a package. Furthermore, because many packages involve a vertical form, fill, and seal machine, it is desirable that the apparatus and method be easily adapted for use on such a machine, preferably with only minor modification and without significantly decreasing bag rates.